Vapor-coating apparatus



Filed July 19, 1965 June 3, 1969 DAUS ET AL VAPOR-COATING APPARATUS Sheet 2 012 Filed July 19, 1965 United States Patent 3,477,506 VAPOR-COATING APPARATUS Donald A. Dans and Robert D. Misch, Chicago, 11]., assignors to MBT Corporation, Chicago, Ill., a corporation of Illinois Filed July 19, 1965, Ser. No. 472,809 Int. Cl. C23c 13/00 U.S. Cl. 118-49 12 Claims ABSTRACT OF THE DISCLOSURE Apparatus for vapor coating synthetic plastic articles such as dentures essentially comprising four containers which include an initial coating substance container for holding an agent which is vaporizable at ambient temperatures, an initial coating container connected to the first mentioned container for holding a synthetic plastic article to be exposed to the vapors of said agent, a final coating substance container for holding an agent which is vaporizable at ambient temperatures, a final coating container connected to the last-mentioned container for holding the synthetic plastic article during exposure thereof to the last-mentioned vaporizable agent, and vapor circulating means including a common conduit and common vapor-generating means for alternately causing vapors from the initial and final coating substance containers to pass into their respective associated containers.

It is known that synthetic plastics, generally speaking, has poor Wettability properties. In those areas of use where wettability is an important consideration, this characteristic of synthetic plastics can detract from the many advantageous attributes of such materials, and can, in certain instances, prevent the user of an article formed of the synthetic plastic from realizing the full benefits of the article. One such area of use is in synthetic plastic dentures. The poor wettability of the plastics from which the dentures are formed contributes, in large meas ure, to a significant number of denture failures. In our copending application Ser. No. 473,212, filed July 19, 1965, and now abandoned, a method is disclosed for substantially reducing the incidence of denture failures from this cause. The present invention provides unique apparatus which is particularly suitable for carrying out the method of our aforementioned copending application.

Briefly, the apparatus of this invention comprises a plurality of containers, at least two of which hold vaporizable substances. Each of the said at least two containers are connected to two other containers for holding plastic dentures to be initially and finally coated by vapors furnished by the vaporizable substances. Circulating means are provided for alternately directing initial and final coating vapors to the plastic denture holding containers. In an especially preferred embodiment of the apparatus, an initial coating substance container is provided for holding a vaporizable coupling or bonding or activator agent to be initially applied to the plastic dentures. This container is connected to an initial coating container for holding plastic dentures to be treated with the vapors of the activator agent. A third container, which may be conveniently called a final coating substance container, is provided for holding a second vaporizable substance which acts, in the vapor phase, to form a substantially water-insoluble, hydrophilic film, coating or layer of silicon dioxide on the activator agent coated plastic dentures. The third, or final coating substance container, is connected to a final coating container for holding the activator agent coated dentures during the final stages of the coating process. The apparatus has vapor conducting means for alternate connection to the initial coating container and to the final coating container, and vapor circulating means including an oscillating suction pump are provided for both vaporizing the vaporizable substances and directing the vapors thereof into the initial and final coating container. In addition, air-intake means including moisture absorbing means are connected to the initial and final coating substance containers, and indicator means are provided to enable an operator to know when the initial and final coating of the dentures has been completed. The apparatus is simple and economical to operate. It is light in weight and compact making it suitable for use by both dentists and dental laboratories.

These and other subjects, advantages and features of the present invention will become apparent from the following description presented in conjunction with the accompanying drawings wherein:

FIG. 1 is a view in perspective of an embodiment of the apparatus of the present invention;

FIG. 2 is a vertical sectional view taken substantially along line 22 of FIG. 1;

FIG. 3 is a vertical sectional view taken substantially along line 3-3 of FIG. 1;

FIG. 4 is a vertical sectional View taken substantially along line 44 of FIG. 1;

FIG. 5 is a vertical sectional view taken substantially along line 55 of FIG. 1; and

FIG. 6 is a schematic view of the various cooperating containers of the said embodiment of the apparatus, and including the vapor circulating suction pump and its associated motor and switch.

In the embodiment of the present invention illustrated, the vapor coating apparatus desirably comprises a support or base member 12, fabricated of plastic, wood, or the like, on which rests a housing 14, preferably formed of a lightweight but rigid plastic material. The bottom edge of the housing 14 may be secured to the base member 12 in any suitable manner. As shown, the base member 12 is formed with strips or raised portions 16 on the upper surface thereof for engaging a shoulder 18 formed in the bottom edge of the housing 14. This arrangement, While adequately preventing lateral movement of the housing 14 with relation to the base member 12, enables the housing 14 to be readily lifted off the base member 12.

The upper surface of the housing 14 is stepped to pro vide an upper container holding portion 22 and a lower container holding portion 24. The upper portion 22 has a pair of spaced, large-container-receiving openings 2626. Positioned between the openings 2626 in the upper portion 22 are an indicator light 28 and a switch 30 the function of which will become clear as the description proceeds. The lower portion 24 has a pair of large-containerreceiving openings 32-32 positioned substantially opposite to the openings 2626 in the upper portion 22, a pair of small openings 3434 located at the ends of the lower portion 24, and a central, small opening 36 situated substantially centrally of the lower portion 24 between the large openings 32-32 thereof. The central opening 36, at its lower end, opens into a recess 40 in the housing 14.

One of the openings 26-26 in the upper portion 22 of the housing 14 receives a substantially cylindrical initial coating container 42 having a snug-fitting cap or lid 44 provided with a gasket 45, and the other of the openings 26-26 receives a substantially cylindrical final coating container 46 having a snug-fitting cap or lid 48 provided with a gasket 49. The container 42 is not as deep as the container 44, and rests on a horizontal wall portion 50. The wall portion 50 has an opening 52 therethrough which is in register with an opening 54 through the bottom wall of the container 42. The opening 54 is provided with a nipple 55 which extends downwardly through the opening 52. The container 46 is of suflicient depth to enable it to be supported on the upper surface of the base member 12, and is provided with an opening 56 through the vertical wall thereof near its base. The container 42 and 46 advantageously are each fabricated of a chemical-resistant plastic, and the walls thereof are of a thickness to resist collapsing due to any differences in pressure internally and externally of the containers during operation of the apparatus.

One of the openings 3232 in the lower portion 24 of the housing 14 receives an initial coating substance container 60 having a two-hole stopper 62. The other of the openings 3232 receives a final coating substance container 64 having a two-hole stopper 66. The containers 60 and 64 may be fabricated of any suitable chemicalresistant material. In the embodiment of the invention illustrated, the container 60 and 64 are made of glass. The stoppers 62 and 66 may be of the conventional type used in chemistry laboratory procedures.

The container 60 is connected to the container 42 by a conduit 70, one end of which extends through one of the holes in the stopper 62 and the other end of which engages te nipple 55 secured in the opening 54 and which extends downwardly through the opening 52 in the wall 50 of the housing 14, As illustrated in FIGS. 1 and 2, the conduit 70 desirably is separated into two sections which are joined together by a separable coupling 71 having a female portion 72 and a male portion 73. This arrangement, among other things, facilitates connection and disconnection of the containers 42 and 60.

The container 64 is connected to the container 46 by a conduit 74, one end of which extends through one of the holes in the stopper 66 and the other end of which carries a male portion 75 of a separable coupling and engages the female portion 76 thereof secured in the opening 56 in the side wall of the container 46. As in the case of the conduit 70, the conduit 74 desirably is separated into sections which are joined together by means of a separable coupling 77 having a male portion 78 and a female portion 79.

One of the openings 3434 in the lower portion 24 of the housing 14 receives a substantially cylindrical air-intake tube 80 and the other of the openings 34-34 receives a similarly shaped air-intake tube 82. The lower end of the tube 80 has a stopper 83 provided with an airintake opening 84. The upper end of the tube 80 has a one-hole stopper 86. The tube 80 is connected to the container 60 through a conduit 88, one end of which extends through the hole in the stopper 86 and the other end of which extends through the other of the two holes in the stopper 62 and terminates at a point just above the bottom of the container 60. The lower end of the air-intake tube 82, like the tube 80, has a stopper 92 provided with an air-intake opening 94, and a one-hole stopper 96 positioned at the upper end thereof. The tube 82 is connected to the container 64 through a conduit 98, one end of which extends through the hole in the stopper 96 and the other end of which extends through the other of the two holes in the stopper 66 and terminates at a point near the bottom of the container 64.

The tubes 80 and 82 each contain a quantity of a moisture absorbing or drying agent 102 to enable moisture in the air passing through the tubes to be reduced to a practicable minimum. A plug 104 of glass wool, or the like, is positioned above each of the stoppers 83 and 92 to separate the agent 102 from the air-intake openings in the stoppers. Exemplary of moisture absorbing agents that can be used in the apparatus are calcium sulfate, silica gel, alumina, and the like. Especially good results are attained with an anhydrous calcium sulfate sold under the trademark Drierite.

The central opening 36 in the lower portion 24 of the housing 14 advantageously receives a substantially cylindrical, transparent indicator tube 110 having a stopper 112 at the upper end thereof and a stopper 114 at the lower end thereof. The stopper 112 has a vertical passage 116 which opens into the tube 110. The passage 116 at its upper end intersects with a horizontal passage 118. The indicator tube is alternately connectable to the containers 42 and 46 by a conduit 120, one end of which is connected to a nipple 121 secured in the passage 118. The other end of the conduit 120 carries a male coupling portion 122 of a separable coupling and is removably connectable to the container 42 through a female coupling portion 124 of a separable coupling secured in an opening 126 in the side wall of the container 42 at the upper end thereof, and is removably connectable to the container 46 through a female coupling portion 128 of a separable coupling secured in an opening 130 in the side wall of the container 46 at the upper end thereof.

The stopper 114 of the indicator tube 110 has a vertical passage 132 which opens into the tube 110. The passage 132 at its lower end intersects with a horizontal passage 134. The passage 134 is connected to an oscillating suction pump through a conduit 142 which engages a nipple 143 secured in the passage 134. An exhaust conduit 144 is provided for the pump. The pump 140 is operated by a motor which is energized by closing the switch 30 connected in series circuit relation with the motor 150 and a power source (not shown). Closing of the switch 30 energizes the indicator light 28 which is connected in parallel to the motor 150 and the power source. The light 28 serves to indicate when the switch 30 is in an on condition. An ordinary light cord 154 is provided for connecting the apparatus to a power source.

The indicator tube 110 advantageously contains a quantity of an alkaline absorber material which serves to absorb vapors passing into the tube 110 from the container 46. A filter 156 is secured in the tube 110 in spaced relation to the stopper 114 to hold the material 160 above and away from the passage 132. The absorber material 160 contains an acid indicator whichchanges color when the pH of the absorber material reaches a predetermined level. This change in color enables the operator of the device to accurately control the exposure time of the dentures to the vapors in the containers 42 and 46. Any alkaline absorber material may be used for this purpose. The indicator used with the absorber material desirably should manifest a change in color at a pH of from about 1 to about 3. Exemplary of absorber materials that can be employed are soda lime, bicarbonate of soda, and the like. Excellent results are attained with an alkaline absorber material sold under the trademark Sodasorb (Dewey and Almy) which contains an acid indicator satisfying the aforementioned pH level conditions.

As shown in FIGS. 2 and 4, a wire, open-mesh receptacle or basket 164, having a handle 166, is provided for the apparatus for holding denture 168 while they are being exposed to the vapors in the containers 42 and 46. A dividing wall 170 is positioned centrally in the basket 164 to keep the dentures separated during processing. When the basket 164 is in the container 42, it is conveniently supported on the bottom of the container. When the basket 164 is in the deeper container 46, on the other hand, it advantageously is supported on a stand 172.

The method of providing plastic dentures with a hydrophilic or wettable surface, and the chemicals utilized in carrying out the method, are described in our copending application Ser. No. 473,212, filed July 19, 1965, and now abandoned. As indicated hereinabove, the apparatus of the present invention, while having general utility as a vapor coating apparatus, is especially suitable for use in treating plastic dentures in accordance with the method of our aforementioned copending patent application. Accordingly, the operation of the apparatus of this invention will be described in relation to its suitability for treating such articles.

Referring now in particular to FIG. 6 of the drawings, before the pump 140 is activated by closing the switch 30, one end of the conduit 120 is connected to the passage 118 in the stopper 112 through the nipple 121, and

the male coupling portion 122 at the other end of the conduit 120 is connected to the container 42 through the female coupling portion 124. The stopper 62 is then removed from the container 60 and a quantity of the coupling or bonding or activator agent is poured therein. As described in our aforementioned copending application, the activator agents used at this stage in the treatment of plastic dentures desirably are monomeric organic silicon compounds, or silanes, having at least one unsaturated aliphatic group bonded to silicon by a carbon-to-silicon bond. Exemplary of such compounds are vinyltrichlorosilane, vinylallyldichlorosilane, allyltrichlorosilane, and the like. After replacing the stopper 62 on the container 60, the dentures 168, which have been thoroughly cleaned and dried, are placed in the basket 164, and the basket, in turn, is set in the container 42.

After the cover 44 has been securely positioned on the container 42, the switch 30 is closed to energize the motor 150 and activate the pump 140. The pump .140 draws air through the opening 84 in the air-intake tube 80 and brings it into contact with the moisture absorbing or drying agent 102 contained therein. The dried air from the tube 80 passes through the conduit 88 into the container 60 where it mixes with the vapors of the coupling or bonding or activator agent in the container 60. The airvapor mixture then passes out of the container 60 through the conduit 70 and into the initial coating container 42 where it contacts the dentures 168. Excess activator vapors are withdrawn from the container 60 through the conduit 120 and into the indicator tube 110. In the tube 110, the vapors come into contact with the indicator containing alkaline absorber material 160 and are absorbed. The vapor-free air passes into the pump 140 through the conduit 142 and out the exhaust conduit 144 to atmosphere. As excess activator vapors continue to pass from the container 42 into the indicator tube 110, the uppermost portion of the alkaline absorber material 160' will manifest a change in color signalling that the initial coating operation is near completion. The switch 30, thereupon, is opened to de-energize the motor 150 and stop the pump 140.

The dentures are allowed to remain in the container 42 for approximately five minutes. During this interval, a final coating agent is poured into the final coating substance container 64. As described in our aforementioned copending application, the final coating agent advantageously is a hydrolyzable silane exemplified by such halosubstituted silanes as tetrachlorosilane and tetrabromosilane.

Before transferring the dentures 168 from the initial coating container 42 to the final coating container 46, the activator vapors desirably first are flushed from the container 42. This can be accomplished by simply separating the two portions of the coupling 71 and then closing the switch 30 to energize the motor 150 and activate the pump 140. The excess vapors in the container 42 are thus drawn out through the conduit 120 into the indicator tube 110 where they are absorbed by the material 160. The motor 150 is then de-energized by opening the switch 30, and the basket 164, containing the dentures 168, is transferred to the final coating container 46 and placed on the stand 172 as shown in FIG. 4. The cover or lid 48 should be snugly and securely positioned on the container. Following transfer of the basket 164 and the dentures 168 to the container 46, the male coupling portion 122 carried by the conduit 120 is disconnected from the female coupling portion 124 secured in the opening 126 in the container 42 and connected to the female coupling portion 128 secured in the opening 130 of the container 46. The motor 150 is again energized by closing the switch 30. The pump 140 draws air through the opening 94 in the tube 82. As the air passes upwardly through the tube 82, it is brought into contact with the drying agent 102 contained therein. The dried air passes out of the tube 82 and through the conduit 98 into the container '64. The

dried air causes a portion of the final coating substance in the container 64 to vaporize, and the vapors thereupon pass out of the container 64 and through the conduit 74 into the container 46. The container 46 is of a size and depth to favor the hydrolysis reaction that takes place between the final coating substance vapors from the container 64 and the moisture present in the ambient air present in the container 46.

The final coating operation generally takes about ten minutes to complete. As a result of the hydrolysis reaction which takes place in the container 46, an acid, in vapor form, is evolved which is continuously withdrawn from the container 46 by the action of the pump through the conduit 120 into the indicator tube 110. This by-product of the hydrolysis reaction is absorbed by the alkaline absorber material 160 contained in the tube 110. When the material 160 has absorbed a sufiicient quantity of the acid vapors to bring the pH of the material 160 to a level at which the acid indicator contained therein is activated, the material 160 will manifest a. change in color. This color change generally is progressive, and will be evident throughout the material 160 at about the time that all of the final coating substance in the container 64 has been evaporized. The motor is thereupon deenergized by opening the switch 30, and the basket 164, containing the dentures 168, is removed from the container 46. The dentures 168 then are cured by simply exposing them to the atmosphere for about 30 minutes. The entire operation can be performed in a minimum of time and does not require any special mechanical skill. The apparatus is fool-proof and consistent in operation, and maintenance costs are, for all practical purposes, negligible.

While, as stated previously hereinabove, the apparatus of this invention has been described with reference to a preferred embodiment and special use thereof, it should be understood that the apparatus can be effectively used to vapor coat synthetic plastic contact lenses, spectacle lenses, camera lenses, and the like, as Well as various and sundry plastic articles where surface wettability and/or hardness is important to the full, practical and satisfactory utilization thereof. Thus, it will be understood that vari ous modifications may be made in the apparatus as de scribed without departing from the spirit and scope of the invention.

What is claimed is:

1. Apparatus for vapor coating materials comprising an initial coating substance container for holding a va- .porizable agent, an initial coating container connected to said first mentioned container for holding a material to be exposed to the vapors of said agent, a final coating substance container for holding a vaporizable agent, a final coating container connected to said last mentioned container for holding said material during exposure thereof to said last mentioned vaporizable agent, and vapor circulating means including a common conduit and common vapor-generating means for alternately causing vapors from said initial and final coating substance containers to pass into their respective associated containers.

2. Apparatus for vapor coating materials comprising an initial coating substance container for holding a vaporizable agent, an initial coating container connected to said first mentioned container for holding a material to be exposed to the vapors of said agent, a final coating substance container for holding a vaporizable agent, a final coating container connected to said last mentioned container for holding said material during exposure thereof to said last mentioned vaporizable agent, vapor conducting means including a common conduit for alternate con nection to said initial coating container and to said final coating container, and common vapor-generating means cooperating with said common conduit for alternately causing vapors from said initial and final coating substance containers to pass into their respective associated containers.

3. Apparatus for vapor coating synthetic plastic materials to provide the surface of such materials with a substantially water-insoluble, hydrophilic coating of silicon dioxide comprising an initial coating substance contaner for holdng a vaporizable bonding agent, an initial coating container connected to said first mentioned container for holding a plastic material to be exposed to the vapors of said bonding agent, a final coating substance container for holding a vaporizable agent capable of forming a coating of silicon dioxide on the bonding agent coated plastic material, a final coating container connected to said last mentioned container for holding the bonding agent coated plastic material during exposure thereof to the vapors from said final coating substance container, and vapor circulating means including a common conduit and common vapor-generating means for alternately causing vapors from said initial and final coating substance containers to pass into their associated containers.

4. Apparatus for vapor coating synthetic plastic materials to provide the surface of such materials with a substantially water-insoluble, hydrophilic coating of silicon dioxide comprising an inital coating substance container for holding a vaporizable bonding agent, an initial coating container connected to said first mentioned container for holding a plastic material to be exposed to the vapors of said bonding agent, a final coating substance container for holding a vaporizable agent capable of forming a coating of silicon dioxide on the bonding agent coated plastic material, a final coating container connected to said last mentioned container for holding the bonding agent coated plastic material during exposure thereof to the vapors from said final coating substance container, vapor conducting means including a common conduit for alternate connection to said initial coating container and to said final coating container, and common vapor-generating means cooperating with said common conduit for alternately causing vapors from said initial and final coating substance containers to pass into their respective associated containers.

5. Apparatus as claimed in claim 3 wherein humidity control means is associated with said initial and final coating substance containers.

6. Apparatus as claimed in claim 3 wherein indicator means is associated with said final coating container :for indicating the completion of the final coating of said plastic material.

7. Apparatus as claimed in claim 3 wherein said vapor generating means includes a suction pump.

8. Apparatus for vapor coating materials comprising a plurality of containers at least two of which hold a vaporizable substance, each of said at least two containers being connected to another container for holding material to be vapor coated by the vapors of said substance, and vapor circulating means including a common conduit and common vapor-generating means for alternately directing vapors from each of said at least two containers to its associated said other container.

9. Apparatus for coating articles formed of methyl methacrylate polymer to provide the surface of the articles with a substantially water-insoluble, hydrophilic coating of silicon dioxide comprising: an initial coating substance container for holding a vaporizable bonding agent, an initial coating container connected to said first mentioned container for holding an article formed of methyl methacrylate polymer to be exposed to the vapors of said bonding agent, a final coating substance container for holding a vaporizable agent capable of forming a coating of silicon dioxide on the bonding agent coated article, a final coating container connected to said last mentioned container for holding the bonding agent coated article during exposure thereof to the vapors from said final coating substance container, air passage means connected to said initial and final coating substance containers, and circulating mean including a common conduit and common vapor-generating means for alternately causing air to pass through said air passage means into said initial and final coating substance containers to effect vaporization of the vaporizable agents contained therein and circulation of the vapors into the associated initial and final coating containers ofv said coating substance containers.

10. Apparatus as claimed in claim 9 wherein vapor exhaust means is provided for said initial and final coating containers.

11. Apparatus for coating plastic dentures with a substantially water-insoluble, hydrophilic coating of silicon dioxide to improve the wearer tolerance characteristics of the dentures, comprising: an initial coating substance container for holding a vaporizable bonding agent compatible with the plastic of the denture, an initial coating container connected to said first mentioned container for holding a plastic denture to be exposed to the vapors of said bonding agent, a final coating substance container for holding a vaporizable agent capable for. forming a coating of silicon dioxide on the bonding agent coated plastic denture, a final coating container connected to said last mentioned container for holding the bonding agent coated plastic denture during exposure thereof to the vapors from said final coating substance container, air intake means including moisture absorbing means connected to said initial and final coating substance containers, vapor circulating means including a common conduit and a single suction pump for alternately causing air to pass through said air intake means and into said initial and final coating substance containers to effect vaporization of the vaporizable agents contained therein and passage of the vapors into their associated containers, vapor exhaust means alternately connectable to said initial and final coating containers, and indicator means for indicating the completion of the final coating of the plastic denture.

12. Apparatus as claimed in claim 11 wherein said vapor exhaust means is connected to said suction pump.

References Cited UNITED STATES PATENTS 1,866,346 7/1932 Clark 1l858 X 2,671,739 3/1954 Larder 118-49 X 2,749,255 6/1956 Nack et a1. 118-49 X 3,020,128 2/1962 Adcock et a1.

3,171,755 3/1965 Reuschel et a1. 118-495 X 3,294,059 12/1966 Barnes et al 11849.5

WALTER A. SCHUL, Primary Examiner.

ROBERT I. SMITH, Assistant Examiner. 

